include/netdb.h: Do not define IDN-related flags.

include/netdb.h: Do not define IDN-related flags.

getaddrinfo() does not implement IDN encoding, and always fail when
provided an IDN flag (e.g., AI_IDN) with EAI_BADFLAGS.  Some packages
(such as the VLC media player) check for AI_IDN before they use it;
providing an unimplemented AI_IDN in the libc makes these package
fail.  As a result they make calls to getaddrinfo() with AI_IDN that
always fail while they could have made successful calls without AI_IDN
instead.

Thus, do not define IDN flags: it is better not to compile rather than
to compile a code that always fail.

Signed-off-by: Thomas Claveirole <[email protected]>